facebook_like.rb

class FacebookLike < ActiveRecord::Base


  belongs_to :user

  validates :facebook_id, :user_id, :facebook_created_at, :presence=>true

  def self.graph
    @graph ||= Koala::Facebook::GraphAPI.new(access_token)
  end

  def self.update_likes_for_user!(user, opts={})
    results = graph.get_connections(user.facebook_id, 'likes', opts)
    loop do
      results.each do |hash|
        unless user.facebook_likes.exists?(:facebook_id=>hash['id'])
          user.facebook_likes.create!(
              :facebook_id        =>hash['id'],
              :name               =>hash['name'],
              :category           =>hash['category'],
              :facebook_created_at=>hash["created_time"])
        end
      end
      results = results.next_page
      break if results.nil?
    end
  end


  def self.real_time_update!(payload)
    RealtimeUpdate.new(payload).enqueue_updates!
  end


  class RealtimeUpdate < Struct.new(:payload)


    def enqueue_updates!
      remove_duplicate_uids.each do |entry|
        if (user = Authentication.find_by_uid_and_provider(entry['uid'], 'facebook').try(:user))
          Resque.enqueue(ResqueJob::UpdateFacebookLikes, user.id, :since=>entry['time'])
        end
      end
    end

    protected

    def remove_duplicate_uids
      payload['entry'].each_with_object({}) do |entry, hash|
        hash[entry['uid']] ||= [] << entry
      end.values.collect { |update_payloads| update_payloads.min { |entry1, entry2| entry1['time']<=>entry2['time'] } }
    end


  end


end

facebook_payload.json

{ "entry" : [ { "changed_fields" : [ "likes" ],
        "id" : "100000177646258",
        "time" : 1305944959,
        "uid" : "100000177646258"
      },
      { "changed_fields" : [ "likes" ],
        "id" : "100001645019389",
        "time" : 1305944959,
        "uid" : "100001645019389"
      },
      { "changed_fields" : [ "likes" ],
        "id" : "100001645020199",
        "time" : 1305944960,
        "uid" : "100001645020199"
      },
      { "changed_fields" : [ "likes" ],
        "id" : "100001645021160",
        "time" : 1305944961,
        "uid" : "100001645021160"
      },
      { "changed_fields" : [ "likes" ],
        "id" : "100000965063713",
        "time" : 1305944961,
        "uid" : "100000965063713"
      },
      { "changed_fields" : [ "likes" ],
        "id" : "1143374968",
        "time" : 1305944961,
        "uid" : "1143374968"
      },
      { "changed_fields" : [ "likes" ],
        "id" : "100001645020645",
        "time" : 1305944963,
        "uid" : "100001645020645"
      },
      { "changed_fields" : [ "likes" ],
        "id" : "100001257359854",
        "time" : 1305944962,
        "uid" : "100001257359854"
      }
    ],
  "object" : "user"
}

facebook_updates_controller.rb

class FacebookUpdatesController < ApplicationController

  VERIFY_TOKEN = "wekghonepkehidmo"

  layout nil

  def create
    FacebookLike.real_time_update!(params)
    render :text=>'success'
  end

  def index
    Rails.logger.info("FacebookUpdatesController verification")
    render :text=>Koala::Facebook::RealtimeUpdates.meet_challenge(params, VERIFY_TOKEN)
  end

end

Gemfile

gem 'koala'
gem 'resque'

routes.rb

Weshop::Application.routes.draw do

  resources :facebook_updates, :only=>[:create, :index]

subscribe_realtime_fb_updates.rb

updates = Koala::Facebook::RealtimeUpdates.new(:app_id => app_id, :secret => secret_key)
updates.subscribe("user", "likes", "http://www.cowhoppedcommodore.biz/facebook_updates", FacebookUpdatesController::VERIFY_TOKEN)

update_facebook_likes.rb

class ResqueJob::UpdateFacebookLikes

  @queue        = "facebook_likes"

  def self.perform(user_id, opts={})
    ::Timeout.timeout(1800) do
      FacebookLike.update_likes_for_user!(User.find(user_id), opts)
    end
  end

end